Application of Non-PCI Gigabit Ethernet Controller AX88180 in Embedded System

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The AX88180 is a high-performance, low-cost Non-PCI Gigabit Ethernet controller from Taiwan ASIX. It complies with IEEE802.3/IEEE802.3u/IEEE802.3ab protocol and is suitable for a variety of embedded systems requiring high-speed access networks. The system has a wide range of applications in streaming media, multimedia networks, high-bandwidth transmission, etc., such as audio and video content distribution, IP set-top boxes, digital recorders, DVD recorders, high-definition TVs, digital media adapters, home gateways, and IP TVs. Wait.

2 internal structure

The AX88180 has a built-in 10/100/1000Mb/s Ethernet Media Access Controller (MAC) and an RGMII interface with the PHY: a built-in host interface controller that can be easily connected to a 16/32-bit host in the same addressing mode as the SRAM. Built-in 40KBSRAM network packet buffer, of which 32KB is used to receive data packets from the PHY. 8KB is used by the host to send data packets to the PHY, which can store, retrieve and modify the packet in an efficient manner; built-in 256-byte configuration register for host control and parameter setting; built-in EEP-ROM interface; built-in IP/TCP/ UDPchecksumoffloads can greatly reduce the computing load of the microcontroller and improve the transmission response time. Figure 1 is a block diagram of the internal structure of the AX88180.

3 main pin functions and distribution

The AX88180 has 128 pins and is mainly divided into RGMII interface, HOST interface, EEPROM interface, power interface, and other interfaces. Figure 2 shows the pinout of the AX88180. Tables 1 and 2 show the pin functions of the RGMII and HOST interfaces, respectively.

4 system principle

The AX88180 has a 16/32-bit host interface that can be directly connected to the embedded microprocessor. The host can operate like an SRAM. The host allocates a 64KB of storage space to the AX88180, of which 0000H-7FFFH is used for data reception and reception. When the AX88180 sends an interrupt to the host, the host reads the address and reads the received data into the system memory, and then the protocol processing program processes it; 8000H-FBFFH is used to send data, and when the system sends data, the host first encapsulates the data. Transfer to this address, then the AX88180 sends the data to the network. The RXII connection is used between the AX88180 and the PHY. Gigabit supports full-duplex, and 10/100Mb/s supports full-duplex and half-duplex modes. Figure 3 is a block diagram of the system components.

5 in high-speed data acquisition system applications

5.1 hardware design

Figure 4 shows an application circuit of an embedded Gigabit network interface in a high-speed data acquisition system. The S3C2440A is a 16/32-bit RISC microprocessor designed for handheld devices and cost-effective, low-power applications. It is connected to the AX88180 in a bus mode, and its address bus, data bus, read/write signals, etc. are directly connected. The clock signal (40MHz ~ 100MHz) of AX88180 is provided by S3C2440A. The interrupt signal of AX88180 is connected with EINT11 of S3C2440A: A simplified Gigabit media independent interface RGMII interface is used between AX88180 and PHY device 88E1111, and the signals are directly connected.

5.2 software design

The program is mainly composed of a protocol program, a driver, an application, and the like. The protocol program can be obtained by the host system transplantation operating system (such as embedded Linux); the driver is mainly composed of an initialization program, a data receiving and transmitting program, and an interrupt service program. Some drivers are available from the manufacturer, while others require the user to write them themselves. The following is the program code for writing the PHY register in the driver:

6 Conclusion

The AX88180 is inexpensive and powerful, and no similar products have been found yet. This article describes its internal structure, functions and principles. And a specific application design is given, which has a good reference for the high-speed access network of embedded systems.

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